DD-PS No. 75.277 discloses a method and a device for the thread-stitching of folded sheets, so that the folded sheets can be stitched in conjunction with web-fed rotary stitching machines. In this reference the folded sheets are continuously moved on a stitiching cylinder; at the same time, they are punctured along a defined section by stitiching needles operating at the same speed, while a stitching or sealing thread is being inserted. The ends of the thread are sealed or glued by passing fixed devices disposed along the circumference of the stitching cylinder.
The stitching cylinder has sheet gripping elements disposed on its jacket, whereby the stitching thread is pressed against the stitching material by means of controllable pressure elements. The stitching needles rotate with the stitching cylinder about a fixed control cam, which initiates the function of the stitching needles that are guided against it by means of pressure springs.
With the high productivity of modern web-fed rotary printing machines, high wear certainly occurs at the guides of the needle motion, and this cannot be compensated for by rapid disassembly of the latter. Furthermore, there is no opportunity to adapt to the expected product spectrum by optional different binding methods. Up to now, there has been no solution for lubrication.
DD-PS No. 138 525 discloses equipment for the puncturing of thread clamps; this equipment likewise works with moving stitching material which are accompoanied by needle guides supported by an endless chain and by needles, that are guided in such a fashion, to insert the sealing thread. The motion of the needles is initiated by an electromagnet and by control cams. This solution has the disadvantage that complex working steps would be associated with the necessity of always replacing all the production elements at th circulating chain. Due to the complex action chain, an increase of production speed is also associated with greter proneness to problems with the equipment.